Can try, but first Welcome to the forum Mart419 !
You will get a PM today, with all you need to know about our forum :) Please read!
..oddRC5 (64bit) won't run.
First of all. Get a new pack!
https://github.com/LMMS/lmms/releases/d ... -win64.exe
Remove current, and also remove the config-file:
https://lmms.io/wiki/index.php?title=LM ... h_Settings
Then how about these:
* Are you installing as admin? Do! -and grant all users access!
* Do you install inside your windows-folder? Dont!